HOUSE FLY. 79 
winter have their further development stopped, and remain in a torpid 
condition till the returning warmth of spring enables them to complete 
their cycle of changes.” With regard to locality of egg deposit, Mr. 
Butler considers that this species (I. domestica) ‘‘ does not select meat, 
but deposits its eggs amongst stable refuse, as the larve feed upon 
horse-dung, of which they eat the softer decaying parts, and leave the 
bits of hay and straw.” * 
Dr. J. Ritzema Bos notes that these flies are very objectionable, 
amongst other reasons, because, although they do not pierce or prick 
with the proboscis, but only suck the perspiration or moisture of the 
skin, they have great fondness for settling by the eyes or on the hands. 
Also our domestic animals are seriously troubled by the great numbers 
of their infestation. ‘‘ Most of the House Flies die in autumn, but some 
live through the winter, and propagate in the spring. Lvery female 
lays about seventy eggs in manure heaps, dead animals (Tierleichen), 
decaying meat, and rotting vegetable matter.’ {| Details of rate of 
development and other useful information is given accompanying. 
In the paper previously quoted from by John Curtis, he gives an 
observation of this species having been found breeding in rotten 
potatoes; and with regard to geographical distribution, he notes that 
he ‘can state from personal observation that the Musca domestica of 
Canada, the United States, Cape of Good Hope, and Hobart Town, 
are identically one and the same species with that of Hngland”; and 
that he thinks ‘it probable that it is to be found in every part of the 
world.” —(J. C.) 
Taking a general view of the life-history of these creatures, it appears 
that they live throughout the year actively or otherwise as temperature 
permits ; that each female lays a great number of minute eggs, some- 
what spindle-shaped, or perhaps better described as cylindrical, blunt 
at one end, and elongated towards the other; these eggs may range 
in number from seventy to one hundred and twenty or more, and may 
hatch in twenty-four hours}; the maggot condition lasting up to a 
week, and the chrysalis state likewise ; but in pamphlet noted below, 
even a much more rapid rate of development has been recorded. ‘The 
point on which there appears to be some difference of opinion, is how 
far the House Fly, Musca domestica, infests moist rotting substances, 
other than horse manure, for laying purposes, and at present this 
point seems to me to rest on good authority that, though horse manure 
* For passages quoted above, see ‘Household Insects,’ by Edw. A. Butler, 
pp. 197 and 200. 
+ ‘Tierische Schadlinge und Nitzlinge,’ von Dr. J. Ritzema Bos. 
t For times of rate of development, see experiments by Dr. Packard, quoted 
p. 25 of ‘ The Principal Household Insects of the United States,’ by L. O. Howard 
and C, L. Marlatt. Bulletin No. 4, New Series. United States Department of 
Agriculture, Washington, U.S.A. 1896. 
